Cedar Waxwing
These guys show up infrequently. We have a holly tree in our front yard, and it had just dropped a bunch of berries on the ground.
At first they flew into the tree itself, and dropped to the ground a few at a time, until there were at least a hundred of them on the ground.
We have read that these are very communal birds, sometimes passing a berry down a line of birds until it gets to one hungry enough to eat it. This looked more like a feeding frenzy than a community dinner!
Then a Mockingbird shows up and runs them off... it apparently has a nest in the area.
"Hey, maybe those guys are on to something!"